Electronic valve for operating on very short waves



1951 R. WARNECKE ET AL 2,565,708 7 ELECTRONIC VALVE FOR OPERATING ONVERY SHORT WAVES 2 Sheets-Sheet 1 Filed May- 21, 1947 INVENTOR ROBERTWARNECKE JEAN BERNIER AGENTS B HH HMMH n Am O m 1951 R. WARNECKE ETAL2,565,708

ELECTRONIC VALVE FOR OPERATING ON VERY SHORT WAVES 2 She ets-Sheet 2Filed May 21, 1947.

INVENTOR ROBERT WARNECKE JEAN BERNIER AGENTS Patented Aug. 28, 1951ELECTRONIC VALVE FOR OPERATING ON VERY SHORT WAVES Robert Warnecke andJean Bernier, Paris, France,

assignors to Compagnie Generale de Telegraphic Sans Fil, a corporationof France Application May 21, 1947, Serial No. 749,468 In FranceSeptember 19, 1942 Section 1, Public Law 690, August 8, 1946 Patentexpires September 19, 1962 4 Claims.

This invention is relating to electronic valves operating on very shortwaves.

It is now well known that certain of the principal phenomena which inthe case of ultrashort waves oppose an eflioient functioning of theordinary valves, are due to the fact that in these valves the highfrequency control signal contributes in communicating to the electronstheir kinetic energy.

In the valves known as velocity modulation, the fundamentaldifii'culties resulting from this process of control, reduction of theinput impedance in particular, have been remedied by employing a highfrequency signal only to cause the velocity of the electrons in movementto be varied periodically by a fraction generally slight, of its value;the modulation in intensity of the current conveyed by the beam beingcarried out later on, in a space called space of collection, by agrouping of the electrons due simply to the effect of the differences oftheir individual velocities. Thus, the high frequency energy necessaryfor the control is very slight, whilst the kinetic energy of theelectrons is taken primarily from the source of continuouspotentialserving to accelerate the electrons.

In spite of its great advantage with respect to the ordinary process ofcontrol used in triodes or other valves of the same nature, theforegoing method is not completely satisfactory since the most efficientelectronic grouping which can be obtained by known means in valves knownas velocity modulation valves, leads-under the best conditions ofconstruction and regulation-to a theoretical output value systematicallylimited and well below 100%; in the case of a longitudinal velocitymodulation transformed into a density modulation by drift of theelectrons in a space free from a held, this extreme theoretical value isabout 58%, it being understood that the efiiciency constitutes the ratioof the high frequency energy given up by the beam to the collector tothe energy spent in the source of continuous current potential servingto accelerate the electrons.

The present invention has for its object to improve considerably theefliciency of all valves which are based, in the main, on a periodicallyvariable transit time of the electrons resulting from the action on thebeam of an adequate system of control, such as velocity modulationvalves with control by longitudinal action or by transverse action of ahigh frequency field.

This invention consists in a particular arrangement and novel design-oithe system of control for amplifier valves; and at the same time of thesystem of control and of the collector system for auto-oscillatorvalves.

The characteristic element common to all valves of the type forming theobject of the invention is a particular arrangement of the system ofcontrol. The improyed design on which this arrangement is based is thesimultaneous action of several high frequency fields of suitable formwhich will be determined hereafter in such manner that the electroniccurrent wave result ing therefrom, lends itself better to a considerableexchange of energy with the high frequency held, or the high frequencyfields of the collector.

It can be proved that the fact that the transit time is sinusoidal butof the form where is the output phase of the electrons from the controlsystem, and 7c is a whole number, produces under the best adjustmentconditions a gain in efficiency of 16%, whilst the form only gives asupplementary gain of 1.4%. It can be shown that the gain made by addingharmonics of higher and higher order to the transit time is less andless although the maximum efliciency thus does tend towards whenapproaching the ideal form Actually, this form expresses the conditionat which all the electrons issuing from, the control system in thecourse of a period pass at the same time into the collector and thiswhen its electric field is a retarding one and a maximum.

It will be easily understood that in order to obtain such optimum formsof the duration of travel of the electrons between the control systemand the collector'system, the disturbance of control must be 'asuperposing of harmonic disturbance. If it were possible to produce indecimetric or centimetric waves potentials of a form freely capable ofadjustment by means of external generators, it would consequently bepossible to improve the efiic'iency' of the transit time generatorswhich the invention has in view, at least when they are used asamplifiers, retroactive or otherwise, up to a value of approximately100% and this without the use of any particular system of electrodes.

according to one characteristic of the invention of making up of thisideal external generator by making us of energy which can be found, inparticular in the interior of the valve, according to anothercharacteristic of the invention.

There will now be described the particular arrangement of the electrodesof the system of control of the valves forming the object of theinvention. The object of this arrangement is to permit an optimumdisturbance or a disturbance close to the optimum disturbance orperturbation to be applied to the beam resulting from the precedinggeneralities by the simultaneous action of several harmonic highfrequency fields.

The embodiment of my invention as described herein is illustrated in theaccompanying drawing in which:

Figures 1a and 1b show, diagrammatically, and respectively the electrodearrangement for longitudinal and transverse action of the high frequencyfield on the beam;

Figure 2 shows diagrammatically a velocity modulated beam tube withlongitudinal control and using a drift space;

Figure 2a is a fragmentary view showing a modification of Figure 2wherein the adjacent cavity resonators are separated;

Figure 3 shows diagrammatically an electrode arrangement for a velocitymodulated beam tube with transverse control;

Figure 4 shows diagrammatically an electrode arrangement for thecollector of the beam tube operating in accordance with a characteristicof the present invention;

Figure 5 is a diagrammatic showing of a velocity modulated beam tubehaving control and collector systems in accordance with my invention andadapted to operate as a self-oscillator;

Figure 6 is a diagrammatic showing of a velocity modulated beam tubewith longitudinal control and employing a deflector field; and

Figure 7 shows diagrammatically a velocity modulation valve withretarding field.

It is necessary to distinguish as to whether the velocity modulationvalve is controlled by longitudinal action or by transverse action ofthe high frequency field on the beam.

(a) For valves controlled by longitudinal action, the system ofelectrodes is diagrammatically illustrated in Figure 1a. It isessentially composed of a series of metallic gratings A, B1, B2, B3 B1of single or multiple meshes located on the path of the electronic beamissuing from the cathode K and disposed perpendicularly to the beam. Forthe convenience of the explanation but without many restrictions as tothe scope of the present invention, it will be assumed that thesegratings are flat, parallel, completely equipotential and ideallypermeable to the electrons. According to the principle of the presentinvention, there are applied between these gratings sinusoidalhorizontal potentials u1=U1 sin wt, u2=U2 sin Zwt, un=Un sin not havingpreferably small amplitudes U1, U2 Un with respect to the continuouscurrent potential U0 corresponding to the mean velocity '00 of theelectrons. Without being restrictive, it will be the same between allthe gratings, that is to say, that all the gratings will be raised tothe continuous potential Uo.

(b) For valves controlled by transverse action, the system of electrodesis illustrated diagrammatically in Figure 11). It is composed of severalpairs of electrodes B1, B2, B3 B1, capable furthermore of being reducedto wires each pair being arranged axially of the beam. It is known thatwith this class of control it is the longitudinal component of the highfrequency field occasioned by the deformation of the field lines at theedges of the electrodes which causes the modulation of longitudinalvelocity necessary for the creation of a wave of utilisable current andthat the frequency of this phenomenon is in general double the frequencyof the high frequency field. Consequently, if m is the pulsation of thefield of the collector there will be obtained between the couples ofdeflection electrodes B1, B2 Bn transverse high frequency fields ofpulsation w/2, 2w/2, 3w2 which can be considered as created bypotentials u1=U1 sin ll/2t, 1L2=U2 sin wt of slight amplitudes withrespect to U0.

Itis quite understood that the diagrams comprising Figures la and 112 donot restrict the scope of the present invention. Thus, the number of theelectrodes and the order in which the high frequency potentials areapplied may be different; the electrodes may be raised to differentcontinuous current potentials, they may be separated by spaces free fromhigh frequency fields as shown in Figure 2a and indicated theoreticallyin Figure 1a, several couples of electrodes may correspond to the samepulsation of the high frequency field; the electrodes of Figure 12) neednot be parallel nor at the same level.

It will be evident to any person skilled in the art that by suitablyregulating the amplitudes of the potentials U1, U2, U3- there may befound at the outlet of the control system a disturbance of velocitynecessary for the transit time of the electrons which approaches theideal law and consequently obtain a higher efiiciency than that which isfound with known valves employing a single oscillating electric fieldfor the control. If, in particular, for valves with longitudinal controlthere is employed a system of three electrodes A, B1, B2 fed by twosinusoidal potentials U1 sin of and U2 sin 20:15, it will be possible toobtain for the ideal valve conceived according to the present inventiona theoretical efiiciency of approximately 73% and this according to Whathas been stated above, with a negligible high frequency control power.

One method of carrying the invention into effect will now be describedwith reference to Figure 2, wherein a velocity modulation valve'withlongitudinal control employing a system of electrodes in which thetransformation of the velocity modulation into density modulation isobtained by drift of the beam in a space free from electric field.

Like most of the examples hereinafter described, the valve hasoscillating circuits comprising resonant spaces of revolution about theaxis of the electron beam, having a profile of retracted form and knownas rhumbatron, but it is to be clearly understood that this particulartype of oscillating circuit is only given by way of example and can beapplied to transit time valves for very short waves, the associatedoscillating circuits of which comprise other systems such as sections oftransmission lines or wave guides.

In Figure 2, an emissive cathode K is shown as heated by a filament F;in front of the cathode K are placed three gratings or grids A, B1 andB2. A and B1 are incorporated in the walls of a rhumbatron R1; B1 and B2in the walls of a rhumbatron R2. The rhumbatrons R1 and R2 areillustrated with a common wall but this particular arrangement is notobligatory and in no way restrictive, as the rhumbatrons R1 and R2 maybe separated by a space in which, for example, there is no field. AFaraday cage 12 formed for example by a metallic tube electricallyeonnects the gratings B2 and M. M and N and MN and NN are the electrodesbetween which the electric field acts which is developedin the energycollector formed by a rhumbatron R3 and others that may be used. Withthe arrangement illustrated in Figure 2, A, B1, B M and N are raised toa constant potential U0. P is an electrode which collects the electronsafter their passage in the collector due to a positive polarisation Upwhich is regulated to a value just sufficient to collect them all. Therhumbatrons R1 and R2 are designed and adjusted in such manner as tohave reciprocally self-oscillation pulsations equal to 2w and w, .0:being the vibration pulsation of the rhumbatron R3 If R1 and R2 areexcited with alternating potentials of pulsations 2c and w and ofsuitable phase so that the fields acting longitudinally of the beam haveslight amplitudes but in the ratio of approximately 1 to 2 according tothe elementary theory developed above, and if, the distance 52M isjudiciously chosen to correspond to the potentials according to the saidtheory, then the duration of transit of the electrons between B2 and Mis given by the equation hereinabove stated and the efiiciency of such avalve will be approximately 73%. This result assumes that the effects ofthe space charge and of the transit time of the electrons in thecollector are negligible, but it will be seen that the efficiency ismuch higher than that of usual velocity modulation valves where thesystem of control only comprises a field of pulsation w' and the maximumemciency of which upon the same hypotheses, is 58%.

As has already been described, the valve illustrated in Figure 2supplying energy on the pulsation is requires two control potentials,one at the pulsation w and the other as the pulsation 2w. As has beenexplained above, these two potentials may be chosen very small byproviding a suitable construction and the corresponding. high frequencypowers may then be very small compared with that which appears in thecollector. A fraction of the latter appearing negligible at first, maythus be taken from the collector R3 and delivered in correct phase intothe rhumbatron R 2 to furnish the excitation at the pulsation w. Thismay be produced by means of the coupling line I shown dotted, connectingthe loops b2 and b3 located respectively in the rhumbatrons R2 and R3(where they surround a magnetic flux). The valve obtairied'rriay then beconsidered as a retroactive amplifier which, excited by an independenthigh frequency source of pulsation 20: supplies energy at the pulsationw. This useful energy may be, as is well known, transmitted to theutilisation load by a line 14 connected to a loop b4 which is located inthe collector.

There will now be briefly described by way of amiaa second example, avelocity modulation valve with transverse control, provided with adevice according to one of the principal characteristics of theinvention.

In this example (Figure 3) the oscillating circuits (L131) (L2B2) and Care formed of sections of a transmission line, K is the cathode, P theelectrode collecting the electrons (at a potential Up 0, with respect toK just sufiicient to collect all the electrons), D is a diaphragmserving at the same time as a focalising lens, B13 2 are the two pairsof electrodes of the control system, G1G2 the grids limiting the highfrequency field of the collector C; D, 131, B2, G1, are at the samecontinuous current potential U0.

L1 is the quarter wave element of the transmission line which, connectedto the pair of electrodes B1 forms an oscillating circuit of pulsation02/2.

L2 is the quarter wave element of the transmission line which, connectedto the pair of elec trodes B2, forms an oscillating circuit ofpulsatiOl'l w.

L'3L"3 are elements of the transmission line which formwith G1G2 anoscillating system of pulsation w.

7 b1 is the coupling loop of L1 with the source S of pulsation (0/2, andis connected to the latter by the line Z1.

ha is the coupling loop of L's with the utilisation circuit 13 and b2 isthe coupling loop of L2 with the source of pulsation w.

L2 can be excited by means of a small part of the energy of thecollector connecting 192 by a line Z to a loop bs placed in the vicinityof L3. The valve can then be considered as a regenerative amplifierwhich, excited by an independent high frequency source of pulsation w/2,delivers energy at the pulsation w.

Regulation takes place by acting on the coupling loops b1, b2, b3, 17's,as also on Z1 and Z.

In order to convert, according to the principle of the presentinvention, the valve with longitudinal control of Figure 2, into anautonomous auto-oscillator, there may be employed an energ'i collectorforming the object of the second principle characteristic of the presentinvention.

This collector is arranged in such mannerthat it causes several highfrequency electric fields (more or less limited) oscillating withpulsations.

w, 2w, 3w to act on the beam which passes through it.

It is composed essentially (Figure 4) of a set of metallic gratings M,N1, N2 N17, which are similar to the gratings A, B1, B2 B2 serving aselements to the system of control of Figure 1a and are arranged in thesame way as those with respect to the beam. M and N1 are incorporated orconnected in a resonant oscillating circuit on a pulsation w, N1 and N2in an oscillating circuit of pulsation 2w, etc. (it will be here notedthat it is not necessary for the high frequency fields of pulsation w,20:, to succeed in this order or be juxtaposed along the beam; they mayfor example be separated by spaces free from fields).

The operation and regulation of this collector of energy are based onthe following observe tions:

As appears from the generalities at the outset, the maximum efficiencyis obtained when the valve is regulated in such manner that the greaterpart of the electrons (if not the whole) issuing from the system ofcontrol in the course of a period, pass at the same instant through thecollector. The collectoris thus excited by impulses of pulsation 10. Onthe other hand, it is well known that impulses of pulsation to permitoscillatory system of pulsation no to be excited. It will thus be easilyunderstood that by acting for example on the shunt impedances of thevarious oscillatory circuits of the above collector it is possible so toarrange that practically the whole of the energy transported by the beamappears in the resonant circuit of pulsation o, whilst there appear inthe oscillating circuit of pulsation 2m, 3w only the energies justsufiicient suitably to excite the system of. control according to theinvention. The valve having to act as a generator for a certainfrequency corresponding to w, it is useless and even injurious for anamount of energy greater than that which is necessary for the control tobe taken from the beam and appear in the circuits tuned to 2w, 30.).

Referring to Figures 5, 6, and 7, there will now be described by way ofexamples, various modifications according to the present invention ofauto-oscillator transit time valves provided with systems of control andwith collectors arranged as described.

The valve illustrated diagrammatically in Figure is a velocitymodulation valve and with drift conversion in a space free from field.It is provided withonly the control electrodes A, B1 and B2 and outletelectrodes M, N; and N2; that is to say, that for the control and thetaking of ener y, only two fields in each case are caused to act, inaccordance with what has been stated above these two fields which arejuxtaposed resonating on 'w and 2w. I

The rhumbatrons R1 and R4 are regulated to resonate on 2w.

The rhumbatrons R2 and R3 are regulated to resonate on w.

To obtain the maximum efficiency of the valve, the shunt impedance of R3is adjusted so that U=Uo and R4 is adjusted to a value just sufficientto enable the energy necessary to excite R1 to be taken from theauxiliary collector so as to produce between A and B1 the oscillatingfield with pulsation2w.

The transfer of energy between the corresponding rhumbatrons will takeplace for example through the lines Z1 and Z2 and magnetic couplingloops b1b"1, b2b2.

The energy which can be employed at the pulsation to will be transmittedto the load by a line 13 and the loop be located in the principalcollector of energy R3.

Figure 6 illustrates diagrammatically a velocity modulation valve bylongitudinal control and with deflector field. The control and.collector sys-, tems as also the coupling systems are similar to thoseof the preceding valve.

The rhumbatrons R1R2R3 and R4 are raised to the same continuous currentpotentials Uo; P at the potential Up 0 is the electrode collectingelectrons and H at the continuous current potential UH is the deflectingelectrode.

Figure '7 illustrates diagrammatically a velocity modulation valve withretarding field; the grouping of the electrons is effected by totalreflection and the system of control operates at the same time as acollector of energy. This is composed essentially of two rhumbatrons R1and R2 of pulsation 2w and raised to the continuous potential U0; P isthe reflectingelectrode, raised to a negative potential with respect tothe cathode K. The electrons coming from K, are modulated in velocity bythe system RiRz grouped in the space R zP and traversing afresh thesystem R1R2 where they give up their energy.

The adjustments of the valve must be such that the energy given'up iseffected almost solely to the advantage of the electromagnetic field ofR2, Whilst there is produced in R1 only a slight exchange of energybetween the electrons returning and the electrons passing out.

It is known that valves with retarding fields and with sinusoidalcontrol have a maximum theoretical efliciency lower than that of driftspace valves. This is due principally to the restrictions of phase andof non-reflection of the electrons by the high frequency field, which donot exist in drift space valves. If, owing to the addition, according tothe present invention, of several high frequency fields, it is possibleto improve the grouping of the electrons and to be left free to acertain extent of the restriction of phase, the restriction ofnon-reflection of the electrons by the high frequency field stillpersists. The latter results in that U /U0 is at the most of the orderof 0.70 instead of 1, and thus the maximum efiiciency is of the order of50% instead of 73%.

The invention is naturally capable of other modifications withoutdeparting from the spirit of the invention.

What we claim is:

1. Electron beam tube comprising, a composite input resonator forproducing a periodic velocity variation of the electrons and constitutedby at'least two side-by-side elementary resonators each comprising agroup of two grids between which there is connected a resonant circuit,means connected to said input resonator providing a drift space forcausing the velocity modulated electron beam to form into bunches whiletraversing this space, and an output resonator connected to said meansfor receiving the radio frequency energy of the bunched electron beamcomprising a resonant circuit tuned to a fundamental frequency withmeans for connection to a utilization circuit, the resonant fundamentalfrequencies of said elementary resonators being chosen respectivelyequal to the said fundamental frequency and harmonics thereof, where nis the number of elementary resonators.

2. Electron beam tube according to claim 1, in which any two of thesuccessive elementary resonators comprise a common grid.

3. Electron beam tube according to claim 1, in which the outputresonator is in the form of a group of elementary resonators of whichthe number and the electrical characteristics are similar to those ofthe input resonator, and coupling means between the elementaryresonators the frequencies of which correspond to each other in theinput and output resonators,

whereby the tube behaves as a generator of waves at the fundamentalfrequency.

4. An electron beam tube according to claim 1, in which the outputresonator is in the form of a group of elementary resonators ofelectrical characteristics similar to those of the input resonator, eachof the elementary resonators of the input resonator being coupled with acorresponding elementary resonator of the output resonator, with theexception of one at least thereof, from among those of which theresonant frequency is an harmonic of said fundamental frequency, andmeans comprising a sinusoidal voltage source outside the tube andcoupling means between said source and said last mentioned res- 9 onatorfor externally exciting it by said harmonic frequency.

ROBERT V/ARNECKE. JEAN BERNIER.

REFERENCES CITED The following references are of record in the file ofthis patent:

Number 10 UNITED STATES PATENTS Name Date Litton A Dec. 8, 1942 LittonDec. 22, 1942 Samuel Oct. 15, 1946 Mouromtsefi et a1. Nov. 19, 1946Alford Aug. 5, 1947 Hansen et a1 Oct. 26, 1948

